In a stringed instrument, such as a guitar or bass guitar, the strings are typically supported at the neck of the instrument and at the bridge, being free to vibrate along their length. Ideally, the supporting points are rigid so that they do not move, flex, or vibrate with the string. Such movement would absorb energy from the string, dampening the sound. The ability of the string to vibrate without dampening is often referred to as a tone sustaining characteristic. Where the instrument utilizes a sound board, the bridge also has the function of transferring the vibrations of the string to the sound board with the minimum of distortion and loss. Both of these requirements are best satisfied by a substantially rigid bridge.
Countering these requirements is a desire for the position of the strings to be adjustable. Musicians have individual preferences for the height of the string above the finger board. The closer the string to the fingerboard, the less effort required in fingering the string. However, if the string is too close, it may buzz against the finger board. Individual height adjustment of the strings is a common approach to meeting the musician's needs.
In an instrument which incorporates frets on the finger board, the octave points of the strings should preferably be aligned with the frets. However, this may not be the case with the instrument as it is originally manufactured. Additionally, the above height adjustment may alter the length of the string, altering the position of the octave points. This suggests that the ability to adjust the length of the strings individually should also be provided to correct the octave point positions.
Traditionally, the string support at the neck of the instrument is fixed, so the above adjustments must be accomplished at the bridge. A wide variety of bridges have been developed and are in use which provide both height and length adjustment for the individual strings. However, this adjustability comes at a cost. The bridge can no longer be a single, rigid piece. Multiple elements must be provided and interconnected to provide the two independent adjustments. Any element which is free to move, linearly or axially, or flex and any connection which allows free play or introduces friction results in a loss of energy and a dampening of the sound. Where sound transfer to the sound board is desired, these losses directly impact the quality and quantity of the sound transferred.
While playing the instrument, the musician's hands and clothing, especially sleeves and cuffs, may frequently come into contact with the bridge, whether incidentally during normal play or intentionally through techniques such as palm muting. Snagged clothing or hands would be detrimental.
There is a need for a bridge which provides individual length and height adjustment for each of the strings while providing a strong, substantially rigid structure. The bridge should resist flexing and movement of any of its individual elements, whether linearly or axially. Ideally the bridge would do so while presenting a smooth snag free face to the musician.